UK's FTSE drops to lowest in around six months

* FTSE closes down 1.6 pct at 6,432.21 points

* Rolls-Royce falls for second day on broker downgrades

* Mining shares under pressure as metal prices fall

* Land Securities (LSE: LAND.L - news) boosted by UBS (NYSEArca: FBGX - news) upgrade

By Sudip Kar-Gupta

LONDON, July 7 (Reuters) - Britain's benchmark equity index dropped on Tuesday to its lowest level in around six months, hit by persistent concerns over Greece and a pullback in mining stocks as metal prices fell.

The blue-chip FTSE 100 index closed down 1.6 percent at 6,432.21 points, around its lowest since mid-January.

Global stock markets lost ground after a Eurogroup meeting of euro zone finance ministers failed to bring about a clearer picture on the outlook for Greece.

Greek voters on Sunday rejected austerity measures imposed as part of a bailout, increasing the risk that Greece may leave the euro zone.

Mining stocks slid after copper prices fell to six-year lows, partly due to concern about economic growth in China, the world's top metals consumer.

"While Greece remains in focus, the volatility in Chinese stock markets has continued, impacting on commodity prices and related sectors such as the miners," Hargreaves Lansdown (LSE: HL.L - news) equity analyst Keith Bowman said.

Rolls-Royce fell 5.4 percent, extending a 6.3 percent drop in the previous session when the company cut profit forecasts, after investment banks Natixis (Paris: FR0000120685 - news) , Investec (LSE: INVP.L - news) , Bernstein and RBC (Other OTC: RBCI - news) all reduced price targets on the stock.

Rolls-Royce was among the weakest FTSE 100 stocks in percentage terms, while property group Land Securities was the top gainer, rising 1.6 percent after UBS raised its rating on the stock to "buy" from "neutral".

The FTSE 100 is down 2 percent this year, and some 10 percent below a record high of 7,122.74 points reached in April. (Additional reporting by Atul Prakash; Editing by Mark Trevelyan)